Structural panel



NOV. 29, 1966 .5, Z. DAsovlC ETAL 3,287,854

STRUCTURAL PANEL Filed Jan. 7, 1965 2 Sheets-Sheerl l ln ven fors STEVE Z. DSOVIC HANS-GUNTHER R. WOLF Nov. 29, 1966 s. z. DAsovlc ET Al.. 3,287,854

STRUCTURAL PANEL Filed Jan. 7, 1965 2 Sheets-Sheet 2 INVENTORS STEVE Z. DASOVIC BY HANS -GUNTHER RJNOLF United States Patent O1 3,287,854 STRUCTURAL PANEL Steve Zlatko Dasovic, 37 Brightside Drive, and Hans- Gunther Richard Wolf, 8 Du Barry Ave., both of West Hill, Ontario, Canada Filed Jan. 7, 1965, Ser. No. 423,966 8 Claims. (Cl. 49-501) The invention relates to a stressed combination structural panel for use in doors and the like.

Structural panels such as are used in assembling doors often comprise a rigid wooden framework and relatively flimsy wooden sheeting such as plywood to cover same, or wooden slats in some cases. However, panels of this type must be made with strong, rigid frames in order to remain fiat and withstand the typical strains experience-d in use, particularly the racking of the frame, and the full economy in construction is not achieved.

The problem lof achieving the necessary rigidity has also obstructed the substitution of plastics for wood in door construction and in fact plastics have been assumed to be uneconomic materials for such purposes. Economies in the amount of plastic used can be achieved by a combination of plastic and wood but this form of construction brings in the further problem of unequal coefficients of expansion which creates built-in stresses which are highly destructive, particularly over substantial lengths or areas.

Accordingly, it is an objective of the present invention to provide a structural panel for use in doors and the like which is for-med of a combination o-f wood and plastic and which is economical in the use of both materials and which is stressed to provide added resistance to usage.

More particularly it is an object of the present invention to provide a panel having the foregoing advantages which permits the expansion and contraction of the wood and plastic at different rates without damage.

More particularly it is an object of the present invention to provide la panel having the foregoing advantages in which a Wooden frame is covered with sheet plastic stressed therearound.

More particularly it is an object of the present invention to provide a panel having the -foregoing advantages in which the wood incorporated therein provides a means of anchoring to the plastic.

The foregoing and other advantages will now be described in the following description of a preferred embodiment of the Iinvention with reference to the following drawings in which like reference device refer to like parts thereof throughout the various views and diagrams and in which:

FIGURE 1 is a perspective of a structural panel according to the invention;

FIGURES 2, 3, 4 and 5 are sections of theembodiment of FIGURE 1 along the lines 2 2, 3 3, 4 4 and 5 5 respectively, of FIGURE l;

FIGURE 6 is a schematic sectional side elevation of the panel of FIGURE 1 at a stage in its construction;

FIGURE 7 is a sectional side elevation of a further embodiment, incorporating the panel of FIGURE 1;

FIGURE 8 is a perspective illustration of a further embodiment of the invention;

FIGURE 9 is a section along the line 9 9 of FIGURE 8 Showing greatly enlarged, the construction of a corner of the embodiment of FIGURE 8',

FIGURE 10 is a section along the line 10 10 of FIGURE 8; and

FIGURE l1 is a cut-away perspective view Showing a further embodiment of the invention.

From FIGURES 1 to 5 it will be seen that the invention comprises a structural panel 10 having a wooden ice frame 11 comprising side portions 12 and end portions 13 fastened together by any suitable means such as rnetal dowels 14 and by gluing. Frame 11 is covered over one sde and its edges =by the box-like plastic member 15 formed in this case of molded sheet plastic material such as polystyrene, polyethylene o-r acrylonitrile butadiene stvrene by vacuum forming techniques. Member 15 has a face portion indicated 'by arrow 16 provided with any desired ,form of decorative design such as ribs 17 to stimulate the transverse slats lof a conventional louvre door (not shown) although any other suitable decorations, or yfunctional design, may be used in any particular case. Member 15 is provided with integral side walls 18 extending there-around substantially normal thereto in the finished article shown in FIGURE l, and suitable attachment smeans such as conventional hinges 19 may be fastened to panel 1f) by any suitable means such as wood screws (not shown) passing through a side wall 18 and into the adjacent side portion 12 of frame 11. Other fastening means or hardware such as door hasp (not shown) may also be attached in a similar manner to any portion of panel 1d if desired.

Due to the differential rates in expansion and contraction experienced as between wood and plastic the attachment between frarne 11 and box-like plastic mem ber 15 is achieved by gluing in certain areas only while leaving other areas of contact between yframe 11 and member 15 free of any attachment whatever. The gluing areas 20 are shown specifically in FIGURES 2, 3, 4 and 5 indicated by reference 20. Thus it will be seen that a layer of glue or other suitable adhesive extends entirely around the interface yof side walls 18 and frame 11, the gluing in this area being designated specifically as 20u. In addition, glue is present at the four corners of frame I1 between the interface of member 15 and frame 11, the gluing in these areas being indie-ated specifically as 2flb. Thus is will be seen that the front or visible surface of panel 1f) corresponding substantially to the area of member 15 is actually bonded to frame 11 only at its four corners, all `other portions being free of bonding and therefore free to move -at differential rates of expansion and contraction independently of one another. Conversely, the side portions 1S are directly bonded to the corresponding faces of frame 11 around the fu'll extent thereof whereby expansion and contraction thereof at differential rates is virtually impossible. However, the prevention of s-uch differential expansion and contraction in such side areas of panel 1li will not produce any serious results, particularly so, lbecause such side areas are generally speaking either completely concealed and invisible or at least not obvious, therefore, @any wrinkling or straining of the plastic material in these areas which may take place will usually pass unnoticed. The method of attachment of member 15 to frame 11 according to this invention may be likened to the attachment of a skin to a drum whereby the principal arca of bonding or attachment is in a plane substantially normal to the plane of the principal stresses which will occur.

In order to achieve a panel 10 of maximum strength and minimum Iweight according to this preferred embodiment, the member 15 is preferably stressed during the process of application and bonding to frame 11 so as to cooperate with frame 11 in resisting strains such as racking strains. In order to achieve such prestressing, member 15 is preferably formed with a degree of warping in its natural state, an example of such warping being shown by member 15 in FIGURE 6. In order to apply a member 15 in this condition to a frame 11, the frame 11 is first treated with glue inthe glue areas 20a and 20b as shown and is then placed in contact with member 15 ready for assembly and gluing. Suitable presses 21 and 22 then apply substantial pressure to member 15 and frame 11 and to side walls 13 of member 15 so as to force member 15 to adopt a completely flat condition and to bend or twist side walls 18 around frame 11 and firmly into contact with the side of the side portions 12 and cross members 13 of frame 11.

While panel 16 as shown in FIGURE 1 may be suitable for providing doors for cupboards or closets, where only the outer face is normally visible, two such panels may be themselves glued back to back, substantially as shown in FIGURE 7, in order to provide a communicating door between two rooms, hinges 19 possibly being clamped between the respective frames 11 of panels 10, as shown, or otherwise aixed in any suitable manner.

According to a further embodiment, illustrated in FIG- URES 8, 9 and 1G, provision may be made for incorporating still further resistance to warping stresses, particularly when utilizing a panel 10 in the construction of a full length door such as the so-called bi-folding door of the type consisting of two door panels 10a and 10b (see FIGURE 8) hingedly jointed together by further hinges 19 and .having upper and lower trunnion means 234 provided for running in a suitable track which may be aiiixed to the upper and lower portions of the door frame (not shown). In order to resist the very severe racking strains experienced in this type of door, additional stiifening is provided in the `form of the steel strip 24 provided down each of the side portions 12 of panels 10a and 10b. Steel strips 24 are preferably fastened in position in recessed portions of side members 12 and extend approximately half way across the ends of the end portions 13 substantially as shown in FIGURE 9, this feature preventing the endwise contact between steel strip Z4 and the side walls 18 of plastic member 15 which might otherwise result in the sidewalls 18 being cut or ruptured by the exposed ends of the steel strip 24. Steel strips 24 are preferably fastened in position by means of suitable wood screws 25 and extend down the full width of frame 11 which cooperates therewith to prevent flexing of steel strips 24 across their thickness. In the embodiment, bonding is achieved between side portions 18 of plastic member and steel strips 24 by any suitable adhesive -in substantially the same manner as described in connection with the embodiment of FIGURE 1. Steel strips 24 are effective to prevent actual warping of units 16a and 10b or bending along their length and flexing of steel strips 24 is prevented by their attachment to frame 11 as described above.

Additional hardware will usually be provided on this type of door comprising handle 26 for sliding the door to and fro and latch 27 for fastening it in its closed position.

A further embodiment of the invention for use in still larger doors and shutters is shown in FIGURE 1l. In this embodiment the side portions 12 of frame 11 are dispensed with and steel strips 24 extend to the full length of frame 11 along each end of end portions 13, being attached thereto by suitable wood screws (not shown). In addition, the plastic member 15 is provided with inturned flanges 28 extending over the back face of frame 11 and a plastic covering sheet 29 is attached over substantially the entire hack surface of frame 11 in order to cover the same and provide a complete door. It will be noted that in this embodiment side portions 18 of member 15 extend only around the side portions 12 of frame 11, end portions 13 being uncovered and -free of attachment in this embodiment so as to permit a limited degree of relative movement, bearing in mind that the complete door may be in excess of six feet in height.

By way of example the plastic member 15 may be formed of sheet plastic of between about .05 and .75 of an inch thick and in the embodiment of FIGURE 8 the steel strip 24 may be between 1A@ and 1,@ of an inch thick. In the embodiment of FIGURE l1 strips 24 will be heavier to withstand the greater stresses.

The foregoing is a description of a preferred embodiment of the invention which is here given yby way of example only. It is not intended to limit the invention to any of the specific features described but the invention comprehends all such variations as come within the spirit and scope of the appended claims.

What we claim is:

1. A combination stressed structural panel and comprising:

a rectangular space frame having side portions and end portions defining front and :back faces, and having side and end surfaces in planes substantially normal so said front and back faces, said side and end portions enclosing a substantially rectangular space;

a thermoplastic frame-covering member extending over the whole 4of said front face and side surfaces, said member covering said rectangular space on one side thereof and being free of attachment to said front face over a substantial proportion thereof permiting relative movement therebetween;

said member comprising a face portion and side portions in planes substantially normal thereto; an adhesive bonding layer ybetween said side portions of said member and said side surfaces vof said frame around substantially the full extent thereof, and a molded pattern formed in said face porti-on of said member and occupying a portion of said rectangular space.

2. A combination stressed structural panel as claimed in claim 1 including metallic stiffening strips extending along said side portions of said frame.

3. A combination stressed structural panel as claimed in claim 1 including adhesive means bonding said member to said front surfaces of said frame at the four corners thereof only.

4. A combination stressed structural panel as claimed in claim 1 including i ange portions on said covering member extending partially around said side portions of said frame and over said back face thereof;

means bonding said member to said side surfaces lof said frame around substantially the full extent thereof and to said back face of said side portions;

and hinge means attached to said frame.

5. A combination stressed structural panel as claimed in claim 1 including hinge means attached to said frame.

6. A combination stressed structural panel as claimed in claim 5 including handle means attached to said frame.

7. A combination stressed structural panel as claimed in claim 1 including a thermoplastic sheet member extending over the full extent of said back face of said frame and bonded thereto.

8. A door structure comprising at least two structural panels, each panel comprising:

a rectangular frame defining front and back faces, and having side surfaces in planes substantially normal to said front and back faces;

a thermoplastic frame-covering member extending over the Whole of said front faces and at least part of said side surfaces, said member 4being free of attachment to sai-d front face over a substantial proportion thereof permitting relative movement therebetween;

means bonding said member to said side surfaces of said frame around substantially the full extent thereof; and means bonding said two panels back-to-back with one another.

(References on following page) References Cited by the Examiner UNITED FOREIGN PATENTS STATES PATENTS 1,030,991 3/1953 France.

Chadwick et al 20n25 1,107,864 8/1955 France. 

1. A COMBINATION STRESSED STRUCTURAL PANEL AND COMPRISING: A RECTANGULAR SPACE FRAME HAVING SIDE PORTIONS AND END PORTIONS DEFINING FRONT AND BACK FACES, AND HAVING SIDE AND END SURFACES IN PLANES SUBSTANTIALLY NORMAL SO SAID FRONT AND BACK FACES, SAID SIDE AND END PORTIONS ENCLOSING A SUBSTANTIALLY RECTANGULAR SPACE; A THERMOPLASTIC FRAME-COVERING MEMBER EXTENDING OVER THE WHOLE OF SAID FRONT FACE AND SIDE SURFACES, SAID MEMBER COVERING SAIDR RECTANGULAR SPACE ON ONE SIDE THEREOF AND BEING FREE OF ATTACHMENT TO SAID FRONT FACE OVER A SUBSTANTIAL PROPORTION THEREOF PERMITING RELATIVE MOVEMENT THEREBETWEEN; SAID MEMBER COMPRISING A FACE PORTION AND SIDE PORTIONS IN PLANES SUBSTANTIALLY NORMAL THERETO; AN ADHESIVE BONDING LAYER BETWEEN SAID SIDE PORTIONS OF SAID MEMBER AND SAID SIDE SURFACES OF SAID FRAME AROUND SUBSTANTIALLY THE FULL EXTENT THEREOF, AND A MOLDED PATTERN FORMED IN SAID FACE PORTION OF SAID MEMBER AND OCCUPYING A PORTION OF SAID RECTANGULAR SPACE. 